Juniper ACX2000 Configuration Guide

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Both of the MAC addresses, 01-1B-19-00-00-00 and 01-80-C2-00-00-0E, are
supported on multiple ports simultaneously to enable maximum flexibility and extension
of existing networks for future deployments. A single PTP port is configured for one of
the MAC addresses at a time.
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PTP packets are sent with the unique MAC address assigned to each port as the MAC
source address. In the PTP packet, the Ethernet frame portion of the packet contains
the Destination MAC field. This field contains either of the two MAC addresses,
01-1B-19-00-00-00 or 01-80-C2-00-00-0E. Also, the Ethernet frame portion contains
the Source MAC field that contains the MAC address of the source port and the
Ethertype field that contains the PTP Ethertype value of 0x88F7. Apart from the
Ethernet frame, the PTP packet contains the PTP payload.
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When you configure a port for PTP over Ethernet to be a slave port, a master port, or
both by having a dynamic port that can be either a master port or a slave port depending
on the states of the other ports in the PTP application, it is possible to build an easily
provisioned, redundant PTP service in an Ethernet ring where every node is configured
as a boundary clock.
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A boundary clock can function as a slave clock to a device using IP (such as a TCA
Series Timing Client or an MX Series router) on one port and can also function as a
slave clock, a master clock, or both on other ports using Ethernet as the encapsulation
method. This behavior occurs within a single PTP domain number.
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Best Master Clock Algorithm (BMCA) and the port state machine are supported to
determine the states of all the ports in a system and the correct state (master or slave)
for a certain port to process PTP packets.
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PTP over Ethernet supports fully redundant and resilient ring-based configurations of
up to 10 nodes for a form of fourth-generation (4G) evolution known as Long-Term
Evolution-Time Division Duplex (LTE-TDD). ACX Series routers support a single node
or link failure and all nodes maintain a phase accuracy of plus or minus 1.5 microseconds
matching a common source.
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You can configure the asymmetry value between the master port and the slave port,
which indicates a value to be added to the path delay value to make the delay
symmetric and equal to the path from the master port to the slave port, on either a
dynamic-state port or a slave-only port.
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You cannot enable PTP over Ethernet on Ethernet interfaces that are configured with
802.1Q VLAN tags or contain a user-configured MAC address.
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While you can configure unique PTP slave interfaces or slave ports with different
encapsulation mechanisms (such as IPv4 and Ethernet), the boundary clock can use
only a single encapsulation method for all of the master ports. Therefore, you must
define either IPv4 or Ethernet encapsulation for all the ports or logical interfaces that
can possibly function as boundary clock masters. Master ports select the link-local
flag based on each port.
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The following limitations apply to the maximum number of ports that you can configure
when you use PTP over Ethernet:
241Copyright © 2017, Juniper Networks, Inc.
Chapter 9: Configuring Timing and Synchronization

Juniper ACX2000 Specifications

General

Brand	Juniper
Model	ACX2000
Category	Network Router
Language	English